2026 PPA National Symposium

Welcome to the 2026 National Symposium!
Thanks to our Platinum Sponsor: Walters Gardens, Inc.
Thanks to our Gold Sponsors: Twixwood Nursery, BASF, New Moon Nursery, and Great Garden Plants
Special thanks to our local planning committee!

Michigan is central in the Great Lakes region and stretches over broad climate and vegetation zones from Eastern Deciduous Forest to Boreal Forest. But this only tells a small part of the story of Michigan’s botanical richness. For example, although Michigan is largely forested, most native upland plants in the flora are not plants of forest understories. Many of the habitats that make Michigan and the Great Lakes region special are open, sunny habitats including dunes, Great Lakes shorelines, rock & sand Barrens, prairies, and prairie openings in open woodland. In these small areas of open habitats occur a substantial proportion of our flora, and many of our rarest plant. Most especially, Great Lakes region endemics (plants found nowhere else except the Great Lakes region), are almost entirely in these open habitats, their evolution presenting interesting problems. Another group of species again almost entirely confined to the northern Great Lakes shores, especially Lake Superior, are plants occurring as rare outliers from their continuous distribution in subarctic and arctic habitats far to the north. These are species that became stranded in special microsites, surviving in these special sites as the flora and vegetation changed around them. Conversely, in the southwest of Michigan occurred a plant community, once extensive, now almost extinct in Michigan – eastern outliers of tall grass prairie, which community especially is a source of many favorite cultivated plants.

Landscape architect and principal of InSite Design Studio Shannan Gibb-Randall has been designing with native plants for over 28 years and has been working towards the sweet spot of design to honor both human and ecological needs. She will share her journey of many hard-won lessons and guidance so that others can engage more deeply with native plant design with success.

Moderated by Laura Robles

As we move into the third education session of our Tuesday program, we look to another influential part of Michigan horticulture, the plant breeding work that has and continues to emerge from this geographic area.

First we’ll consider the importance of ornamental breeding and how advances in perennial breeding have impacted our industry over the recent decades. Wayne Gruber will walk us through this brief “journey in time,” as he discusses how the efforts of perennial plant breeders have impacted the broader industry - from growers to design to retail.

Next, we’ll shift to the work being done today in plant breeding. Dave MacKenzie, Brent Horvath, and Justin Lombardoni will each discuss their current work. By focusing on a particular genera, each will delve into their work, sharing their goals and vision for how these new introductions will continue to move the perennial plant industry forward.

Dave  MacKenzie will be talking about three genera of grasses that he works with, and the surprising amount of bio-diversity that has arisen from his crosses and selections. Andropogon, Panicum and Schizachyrium are widespread in nature and important ecologically, but aren’t always a good fit in the constructed landscape—perhaps too large, too floppy, or simply not the right shape or color. Dave has endeavored to develop “nativars” that fit the constructed world in terms of architectural qualities with the hope that they will bring the same ecosystem benefits to the constructed landscape as they do the natural landscape.

Get the scoop on new introductions from the following companies:

• Plants Nouveau, LLC
• Walters Gardens
• Terra Nova Nurseries Inc
• Pacific Plug & Liner
• Darwin Perennials
• McHutchison
• DeVroomen Garden Products
• Emerald Coast Growers
• Hortech
• PanAmerican Seed

Gardens are not static compositions — they are living systems shaped by time. This talk explores how designing with layered planting, seasonal succession and ecological awareness creates landscapes that grow richer, more resilient and more immersive each year.

Through a range of residential and experimental landscapes, we examine how matrix planting systems, multi-stem trees and carefully composed pathways establish structure while allowing dynamic plant communities to thrive. Lawns give way to biodiverse perennial layers, while microclimates are shaped through canopy, enclosure, planting density, material choices and gentle changes in level. Gravel, steel, water and terracotta interact with planting to build depth and textural contrast.

By embracing self-seeding, habitat creation and year-round interest — from winter scent to late-season seedheads — these landscapes are conceived as evolving ecological tapestries rather than fixed compositions.

 This lecture invites a shift in perspective: to see landscape as a long-term, living framework — where time, texture and ecology are fundamental to creating meaningful and enduring design.